The gauge disclosed in the said patent is adapted to be mounted in alignment with a wheel spindle and includes a spirit level pivotally mounted on a horizontal axis, a rotatable camber indicating wheel which pivotally adjusts said level, and a coaxial caster indicating wheel used in conjunction with the camber indicating wheel. When using this gauge to measure caster, the serviceman first steers the wheel spindle to a predetermined angular position of say 20.degree. to the right of center and then rotates the camber indicating wheel to set the spirit level in the horizontal position. He then rotates the caster indicating wheel to mutually align a pair of reference points respectively provided on the caster and camber indicating wheels. He then steers the wheel to another angular position of say 20.degree. to the left of center and while holding the caster wheel in the set position he rotates the camber wheel to reset the level in the horizontal position. The caster angle can then be read directly from the caster indicating wheel which is graduated for this purpose.
The angles to which the spindle is steered for the caster measurement is established by the manufacturer, and while this procedure is easily followed when aligning the wheels of most vehicles, in some cases it is very difficult if not impossible to mutually align the reference points on the caster and camber indicating wheels because the reference point on the camber wheel is off to the side or hidden by the housing when the camber wheel has been adjusted to set the level in the horizontal position while the wheel spindle is in the required angular position.